In applicant's own prior U.S. Pat. No. 4,761,928, issued Aug. 19, 1988, a sheet metal stud serving as part of the frame of the hollow wall, is described, comprising several pairs of prongs with lateral teeth partially struck out from the web of the stud. The prongs of each pair can be bent transversely to the web alternately on each side of the same just prior to the installation of the insulating panels. Then the latter are engaged over the prongs, which prevent sagging of the panels on each side of the stud. One drawback of the patented stud is the fact that an inexperienced workman can bend all the prongs, or at least the two prongs of one or of several pairs, towards the same side of the stud web, thereby destroying the required alternating direction of successive prongs to obtain a good anchoring of the insulating panels on each side of the stud. If the workman tries to correct his error by bending back the prongs through the web opening which has resulted from the die-cutting of the prong, the retaining zone of the prong to the stud can break under the action of a second bending.
Another drawback of the patented stud relates to the possibility that the workman will set the prong to an oriented position other than its optimum anchoring position. In the above-mentioned U.S. Pat. No. 4,761,928, there are no means enabling the workman to automatically position the prong in its optimum anchoring orientation.